My TTR600 1998 has the speedo drive on the right my XT 600 1987/88 has speedo drive on the left.
The TTR has Pailoi forks which are also fitted to the MZ supermoto and enduro type bike and some CCMs so maybe the wheels are the same.
The swing arm on the TTR is the same as a YZ not sure which year.
I have heard some KTM wheels can be made to fit the TTR by using different spacers.
The TTR has no cush drive but the TTRE has a cush drive, not sure if the swing arms are the same they do look the same.
Why do you want to change wheels.